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Finding the Fourth Proportional to 783.90, 1,177.20 and 419.40

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Solution

The fourth proportional to 783.90, 1,177.20 and 419.40 is: 629.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    783.90 : 1,177.20 = 419.40 : x
  2. Step 2: Convert to fraction form
    783.90/1,177.20 = 419.40/x
  3. Step 3: Cross multiply
    783.90x = 1,177.20 × 419.40
  4. Step 4: Simplify right side
    783.90x = 493,717.68
  5. Step 5: Solve for x
    x = 493,717.68/783.90
  6. Step 6: Final answer
    x = 629.82

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.